This is a Nigerian Slang used commonly in Nigeria to replace the word Problem often.

a pidgin english word used mostly by Nigerians, meaning trouble

Wahala is an African word commonly used in Nigeria to express a state of worry, distress, problem or trouble. It is also called pidgin English. Example- "Why you dey give me wahala?" which means, “Why are you stressing me?” or “Why are you Troubling me?”. Another Example would be, " What is your Wahala" which means, “what is your problem?”. The word Wahala can also be used in another context like " No Wahala". This means, “NO problem”. If somebody asks you How are you? you can say “I dey okay, I no get any Wahala", which means, "I am fine, I do not have any problem".